Initial working fix - Resolves date line related issues. #2048

zach-snell · 2025-03-04T06:28:32Z

Resolves issues around date line and rotation with infinite scrolling longitudinal map. May still need clean up / optimization.

…d dateline and rotation with infinite scrolling longitudinal map. May still need clean up / optimization.

JaffaKetchup

Hi @zach-snell, thanks for opening a PR!

I would be grateful if you could give a little more info as to what this PR fixes.

As I'm testing it, I'm comparing it to the master branch, and I can't see any difference in behaviour. Could you record some videos to show what failed before, and the fixed behaviour with your PR? I'm just struggling to understand why these changes are necessary, particularly with the oscillation fixes, as I've not experienced any oscillations.

As far as I understand, #2019 is completely unrelated to unbounded horizontal scrolling, and instead about issues with the TileLayer not being able to be changed properly. Could you explain how your PR fixes and relates to #2019?

JaffaKetchup · 2025-03-04T10:45:23Z

lib/src/misc/offsets.dart

      if (i == 0) {
        result = addedWidth;
-        bestX = x;
+        bestError = error;
        continue;
      }
-      if ((bestX + ox - halfScreenWidth).abs() >
-          (x + ox - halfScreenWidth).abs()) {
+
+      // Only switch worlds if there's a significant improvement
+      // This prevents oscillation near the boundary
+      if (error < bestError - hysteresisThreshold) {
        result = addedWidth;
-        bestX = x;
+        bestError = error;
      }


Could this be collapsed into a single decision?

I'm also not aware of any situation where oscillation at the boundary is an issue? Did you reproduce this? As far as I understand, this is very different to #2019, but I'm probably missing something.

// Only switch worlds if there's a significant improvement // This prevents oscillation near the boundary if (i == 0 || error < bestError - hysteresisThreshold) { result = addedWidth; bestError = error; }

I'll have to give this a test - I had also noticed that the second assignment of bestX / bestError seemed unused. I knew I would need to review that anyways.

Further, I remember this was related but I was iterating so many times I will confirm if reverting has impact and if so if we can simplify the logic.

lib/src/map/camera/camera.dart

zach-snell · 2025-03-04T12:20:36Z

@JaffaKetchup

You know, I think you're right. I was half asleep I guess and didn't relate the valid issue.

I will record a video showing the issue I was resolving later this morning.

--

The issue was with the way the camera / tiles would flicker or jump from east to west as you move back and forth near the date line.

zach-snell · 2025-03-04T14:43:48Z

Alright - adding some visuals here.
I was way down the rabbit hole through flutter_map plugins related.

I suppose the issues with flickering were at that layer but as I determined I was unable to resolve them there, there had to be a big in the core. That is what brought me to resolving this tiny yet incredibly annoying edge-case where you all luckily had a visual example already built that showed it well.

This shows as the following in main branch

Resolved, no issue with lat/long and screen smoothing

For more context, downstream in flutter_vector_map_tiles
This is after I upgraded a bunch of code to even be able to work with flutter_map 8.1.0.

I do also want to make sure none of my changes are bleeding through - there was a point where I couldn't drag the screen across the 180/-180 area until I adjusted the drag logic but building main this morning it was magically working.

We all know how these things go where magical issues show up and disappear so I will do a bit more testing tonight / after work.

zach-snell · 2025-03-04T21:45:10Z

Turns out I was able to reproduce the dateline issue when I removed the drag logic. I don't know why I couldn't reproduce before. Flutter messing with me - I even ran flutter clean, flutter pub clean, deleted all build artifacts etc but could not reproduce earlier.

Attaching demonstration of that issue and the resolved version.

Demonstrating issue
I know you can't see my mouse here but the stop is pretty obvious as it locks at 180 when I try to drag across.

Working resolution

Feel free to test on main to see if you see the same thing.
Once I reproduced, I was able to quickly change back and forth and hot-reload to see the issue.

I am going to try and isolate a bit to make sure its not self-introduced/resolved.

…ific issue remains.

zach-snell · 2025-03-04T22:40:27Z

Alright! Very much simplified -- turns out there was a chain of self-created issues in there.
I had slowly found the resolution and part of that path introduced unnecessary code which created problems I then resolved.

This should be much easier to review!

JaffaKetchup · 2025-03-20T18:02:30Z

Sorry, been focused on some other PRs. I'm still not sure what this PR is fixing. As far I can see, I can move across the dateline completely fine in the example app on that page.

zach-snell · 2025-03-20T23:06:58Z

Honestly it fixes what seems to be a very small thing that had downstream impacts. It has to do with angles when crossing the dateline causing some of the system to mis-represent the current position. It has been a bit since I messed with it now but that is the jist. The example video you can look for when the dot that stays in one spot on the viewport starts moving in unexpected ways.

…

On Thu, Mar 20, 2025, 1:02 PM Luka S ***@***.***> wrote: Sorry, been focused on some other PRs. I'm still not sure what this PR is fixing. As far I can see, I can move across the dateline completely fine in the example app on that page. — Reply to this email directly, view it on GitHub <#2048 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACRD2YJUAQQX4CIFQOP5MGT2VL7EZAVCNFSM6AAAAABYIXE7QOVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDONBRGI3TAMBUGQ> . You are receiving this because you were mentioned.Message ID: ***@***.***> [image: JaffaKetchup]*JaffaKetchup* left a comment (fleaflet/flutter_map#2048) <#2048 (comment)> Sorry, been focused on some other PRs. I'm still not sure what this PR is fixing. As far I can see, I can move across the dateline completely fine in the example app on that page. — Reply to this email directly, view it on GitHub <#2048 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACRD2YJUAQQX4CIFQOP5MGT2VL7EZAVCNFSM6AAAAABYIXE7QOVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDONBRGI3TAMBUGQ> . You are receiving this because you were mentioned.Message ID: ***@***.***>

JaffaKetchup · 2025-03-20T23:46:15Z

I can't reproduce anything like is shown in the video at all. Are you using a mouse on a real device?

JaffaKetchup · 2025-03-23T11:18:26Z

For the time being, I'm going to close this, because I'm still unsure if there's an issue. Whilst I can see something strange in the screen recording, I can't reproduce this. If you're still having the issue, please file a bug report! Thanks for the contributions anyway :)

Initial working fix - Resolves fleaflet#2019 and related issues aroun…

c7be7cd

…d dateline and rotation with infinite scrolling longitudinal map. May still need clean up / optimization.

zach-snell mentioned this pull request Mar 4, 2025

[BUG] Seamless Tile Updates w/o Blinking? (not sure if actual bug or not) #2019

Open

JaffaKetchup requested a review from a team March 4, 2025 07:39

Fixed formatting issues

53e76fd

JaffaKetchup requested changes Mar 4, 2025

View reviewed changes

JaffaKetchup added 2 commits March 4, 2025 11:06

Update lib/src/map/camera/camera.dart with suggestion

7594c2a

Fixed formatting

12ea190

zach-snell changed the title ~~Initial working fix - Resolves #2019 and related issues around date line~~ Initial working fix - Resolves date line related issues. Mar 4, 2025

zach-snell force-pushed the bugfix/#2019-dateline-smoothing branch from 6b32005 to 12ea190 Compare March 4, 2025 21:41

Reverting unncessary changes - minimum necessary to resolve this spec…

f4ecf7a

…ific issue remains.

JaffaKetchup requested review from a team and JaffaKetchup March 4, 2025 22:55

Merge branch 'master' into bugfix/fleaflet#2019-dateline-smoothing

e10b09b

Merge branch 'master' into bugfix/fleaflet#2019-dateline-smoothing

1a3bc42

JaffaKetchup closed this Mar 23, 2025

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Initial working fix - Resolves date line related issues. #2048

Initial working fix - Resolves date line related issues. #2048

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